allow depth when cloning head commit in branch

posix/clone-commit

@@ -25,13 +25,11 @@ fi
 
 # the commit sha may be empty for builds that are
 # manually triggered in Harness CI Enterprise. If
-# the commit is empty we clone the branch. Note that
-# we intentially omit depth flags to avoid failed
-# clones due to lack of history.
+# the commit is empty we clone the branch.
 if [[ -z "${DRONE_COMMIT_SHA}" ]]; then
 	set -e
 	set -x
-	git fetch origin +refs/heads/${DRONE_COMMIT_BRANCH}:
+	git fetch ${FLAGS} origin +refs/heads/${DRONE_COMMIT_BRANCH}:
 	git checkout -b ${DRONE_COMMIT_BRANCH} origin/${DRONE_COMMIT_BRANCH}
 	exit 0
 fi